// VideoScaleTest.cpp : Defines the entry point for the console application.
// src code is come from ffmpeg realease "./share/ffmpeg/examples/scaling_video.c"
// compile in vs2013 with multi-byte character set
// Modify by Tocy <zyvj@qq.com>.

#include "stdafx.h"

extern "C"
{
#include <libavutil/imgutils.h>
#include <libavutil/parseutils.h>
#include <libswscale/swscale.h>
}

#pragma comment(lib, "libavutil.a")
#pragma comment(lib, "libswscale.a")

void fill_yuv_image(uint8_t *data[4], int linesize[4],
	int width, int height, int frame_index)
{
	int x, y;

	/* Y */
	for (y = 0; y < height; y++)
	for (x = 0; x < width; x++)
		data[0][y * linesize[0] + x] = x + y + frame_index * 3;

	/* Cb and Cr */
	for (y = 0; y < height / 2; y++) {
		for (x = 0; x < width / 2; x++) {
			data[1][y * linesize[1] + x] = 128 + y + frame_index * 2;
			data[2][y * linesize[2] + x] = 64 + x + frame_index * 5;
		}
	}
}

// usage: <executable> <exe_path> <output_file> <outsize>
// as:	  "VideoScaleTest.exe out 176x144"
int _tmain(int argc, _TCHAR* argv[])
{
	uint8_t *src_data[4], *dst_data[4];
	int src_linesize[4], dst_linesize[4];
	int src_w = 320, src_h = 240, dst_w, dst_h;
	enum AVPixelFormat src_pix_fmt = AV_PIX_FMT_YUV420P, dst_pix_fmt = AV_PIX_FMT_RGB24;
	const char *dst_size = NULL;
	const char *dst_filename = NULL;
	FILE *dst_file;
	int dst_bufsize;
	struct SwsContext *sws_ctx;
	int i, ret;

	// input parameter check
	if (argc != 3) {
		fprintf(stderr, "Usage: %s output_file output_size\n"
			"API example program to show how to scale an image with libswscale.\n"
			"This program generates a series of pictures, rescales them to the given "
			"output_size and saves them to an output file named output_file\n."
			"\n", argv[0]);
		exit(1);
	}
	dst_filename = argv[1];
	dst_size = argv[2];

	if (av_parse_video_size(&dst_w, &dst_h, dst_size) < 0) {
		fprintf(stderr,
			"Invalid size '%s', must be in the form WxH or a valid size abbreviation\n",
			dst_size);
		exit(1);
	}

	dst_file = fopen(dst_filename, "wb");
	if (!dst_file) {
		fprintf(stderr, "Could not open destination file %s\n", dst_filename);
		exit(1);
	}

	/* create scaling context */
	sws_ctx = sws_getContext(src_w, src_h, src_pix_fmt,
		dst_w, dst_h, dst_pix_fmt,
		SWS_BILINEAR, NULL, NULL, NULL);
	if (!sws_ctx) {
		fprintf(stderr,
			"Impossible to create scale context for the conversion "
			"fmt:%s s:%dx%d -> fmt:%s s:%dx%d\n",
			av_get_pix_fmt_name(src_pix_fmt), src_w, src_h,
			av_get_pix_fmt_name(dst_pix_fmt), dst_w, dst_h);
		ret = AVERROR(EINVAL);
		goto end;
	}

	/* allocate source and destination image buffers */
	if ((ret = av_image_alloc(src_data, src_linesize,
		src_w, src_h, src_pix_fmt, 16)) < 0) {
		fprintf(stderr, "Could not allocate source image\n");
		goto end;
	}

	/* buffer is going to be written to rawvideo file, no alignment */
	if ((ret = av_image_alloc(dst_data, dst_linesize,
		dst_w, dst_h, dst_pix_fmt, 1)) < 0) {
		fprintf(stderr, "Could not allocate destination image\n");
		goto end;
	}
	dst_bufsize = ret;

	for (i = 0; i < 100; i++) {
		/* generate synthetic video */
		fill_yuv_image(src_data, src_linesize, src_w, src_h, i);

		/* convert to destination format */
		sws_scale(sws_ctx, (const uint8_t * const*)src_data,
			src_linesize, 0, src_h, dst_data, dst_linesize);

		/* write scaled image to file */
		fwrite(dst_data[0], 1, dst_bufsize, dst_file);
	}

	fprintf(stderr, "Scaling succeeded. Play the output file with the command:\n"
		"ffplay -f rawvideo -pix_fmt %s -video_size %dx%d %s\n",
		av_get_pix_fmt_name(dst_pix_fmt), dst_w, dst_h, dst_filename);

end:
	fclose(dst_file);
	av_freep(&src_data[0]);
	av_freep(&dst_data[0]);
	sws_freeContext(sws_ctx);
	return ret < 0;
}

